It's also called as HAPPY PHI DAY.

According to Bloomberg  June 1, 2018 (formatted as 1/6/18 in many parts of the world) is Phi Day, a date that matches the first four digits of the golden ratio.

Represented by the 21st letter of the Greek alphabet, the Golden Ratio  which comes out to roughly 1.618 when rounded, is the number you get when you divide a line into two parts so that the longer part divided by the smaller part is the same as the total length divided by the longer part (o  r simplified : When the smaller is to the larger as the larger is to the whole).

The golden ratio is also closely related to the famous Fibonacci sequence. In this series of numbers beginning with zero or one, each subsequent number equals the sum of the previous two (i.e., 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, etc.). The ratio of any two successive numbers in this sequence comes very close to the golden ratio. Shapes made with Fibonacci dimensions are considered pleasing to the eye, which is why they so often appear in art, either unintentionally or by design.